Scanning apparatus for television



y 1933- H. s. BAIRD SCANNING APPARATUS FOR TELEVISION Filed Nov. 15,1929 2 Sheets-Sheet l uup uunnunuunuuuuuuu UIJDUHDUEIUDUDUUDDUUfhverziof. H-M & a l-S May 16, I933. Hv BA|RD 1,908,809

SCANNING APPARATUS FOR TELEVISION Filed Nov. 15, 1929 2 Sheets-Sheet 2A26 /2 8 w a Patented May 16, 1933 uNiTEo s ms HOLLIS s. BAIBD, or. STNEHAM; 'ivm'sseoriusnrrs, ASSIGNOR, T0 snon'rwnvnfia TELEVISIONCORPORATION, DELAWARE or nes roir MassAeHUsErr'syAff coitroim'rion 0Fscienivme ArrAaA'rUsronfmiinnyisioiv Applicationlfiled November 15,1929. Serial madame; I f

This invention relates to television and particularly to receivingapparatus therefor having picture re-constituting apparatus whichincludes a scanning device provided with 5 small and suitably arrange-dwindows which rotate in front of a light emitting source, the intensityof illumination of which is caused to be varied by the transmittedpicture sig nal. I i

In my cop-ending application Serial No. 366,974, filed May 29, 1929,.1have disclosed a scanning device which consists of an opaque endlessbelt having scanning windows therein and arranged'to be driven insynchronism with the scanning device at the transmitting station. Thebelt preferably is an endless section of a moving picture film and thescanning windows are photographed thereon, the sensitive photographicfilm beingexposed to astrong illumination except at the location of thewindows so that when the film issubsequently developed and fixed, thefilm is opaque except at the windows, where. itis transparent. Y

One of the objects of the present invention is to provide supporting anddriving mechanism for such scanning belt that is relatively free fromnoise when in operation, has few operating parts, and lendsitselfreadily for enclosure within a cabinet which can also contain the signaldetecting and amplifying apparatus essential to the televisionapparatus.

Another object of the invention is the provision of a supporting anddriving mechanism 35 for the belt, which mechanism includes a'scan ningdrum on the periphery of which the scanning belt is supported, .the drumbeing perforated, or having openings, ,at the windows and havingimperforate peripheral portions that are located between and beyond thewindows. a

The drum is driven by a synchronous. motor which has a weak startingtorque Consequently, it is an object of the invention to provide meansby which the motor .canbe started in rotation independently of the drumthereby to reduce the load on the motor at the moment of starting.Specifically, thisobj-ect of the invention comprehenfds a lost-motionconnection between the armature of the mo- .tor and the: drum so .thatthe 'motor canlbegin to rotate. prior to itsengaging and rotatingthedrum. .,f

.Television'signals at present are broadcast .by'radio by means ofscanning-apparatus op .erate'dat various; speeds and havinga variablenumber of scanningwindows; Consequently, .a scanning-belt operated at Yacertain speed and having a certain 'number, of scanning windows, andadaptedfor one particular system ofscanning signals cannot ,receiveintel- 'ligible signals producedby 'a difierently arranged and operatedscanning device. Consequently,another .object of this invention is toprovide-arotatable drum that-is adapted to support scanning belts havingdiiferent .nu'mbersof windows, which; also' may be differently located,on the belt, combined with 111834115 to rOtatethe drum at; various;selected speeds whereby. the device can be adjusted to receivedifi'erenttypes of broadcast [tele- -.vis1on sig'nals. I

While the broadcast aijid receiving stations may operate in%syn'chronismthey yet may be displaced inphas'e,fo'r-Zout of step,;so thatthereceivedfl picture is out of frame. Itis an obj ect. ofthe presentinvention to provide a; simple means? for: -bri-nging; the received.wh'ichfis provi'ded'with' scanning windows, 7

viewing frame located Withouttheperiphery of the drum, and a variablelight source located :within theperiphery of; the drum.

A furtherfobjectis generallyto improve the construction and operation oftelevision apparatus."-.' f; pf j Fig. '1 is a front elevation ofthe'cabinet enclosing the apparatuse'mbodyingthe present invention and,in.itself,;- constituting, a part ofthein-ventionr A r f Fig- 2 is asectional elevation through the cabinet of- Fig. 1 and. illustrating indetail the construction 1 of the app aratustherein, parts of theapparatus not essential to, the present invention being omitted. Fig. ,3is a fr'ontelevati'on of the scanning drum of.Fig-.2 :F-g V1 Fig. 4 is aplan detail of the ap aratus of Fig. 2, parts of the drum being bro enaway.

Fig. 5 is a plan view of a section of the scanning belt associated withthe present invention.

'Fig. 6 is a sectional deteJiL-taksn along line 6-6 of Fig. 2 andillustrates especially the gaseous-conductor lamp and its supportingmeans i 1 I The apparatus embodying the presentinvention is containedwithin the enclosing cabinet 10 having a front wall 12 and atop wall 14which is hinged at 16 to the rear wall 18, the top wall thusconstituting a cover which can be raised to gain access to themeGhanismwithin the cabinet. The movable elements of the television apparatus aresupported upon a base 20 which is carried by the bottom wall 22 of thecabinet. Vertical and peripherally spaced standards 24 upstand from saidbase and support an intermediate. plate 26 and, spaced thereabove, anupper plate 28. A vertical shaft 30 is journalled in bearings 32 in saidplates and has an enlarged annular flange 34 which overlies the upperplate and also has an end 36 which shaft although the drum can beremoved at will from the shaft, both being free from anyposi-tiveattachingmeans. The flange 34 of the shaft is "provided with anupstanding driving pin -46 which is received within a peripherallyelongated groove 48, see Fig. 4,

so that the shaft can have a small amount of initial rotary movementbefore the pin engages a wall of the groove to drive the drum. With thisarrangement, the synchronous driving motor, presently to be described,for the drum can start to rotate freely before it takes on the load ofthe drum. The hub of the drum is seated on the flange '34 and hassuliicient frictional engagement therewith to prevent hunting of thedrum, or its alternate engagement and disengagement the pin 46 when thedrum and shaft are running at synchronous speed. The drum is providedwith upper and lower peripheral- 1y continuous portions '50 and 52respectively which are connected by vertical ribs 54 located within thedrum. The periphery of the drum is provided with'a continuousoutstanding flange or head 56 located at the lower portion of the drumand which con stitutes a stop member that is engaged by the lower edgeof the scanning belt to define its operative position on the drum. The

outer face of the periphery above the bead outer diameter of the drum sothat when the belt is on the drum it is a snug, although readilydetachable, fit thereon. The belt has 7 such width that its upper andlower marginal portions overlie the upperand lower peripherallycontinuous portionsand 52 of the drum. The body of the scanning belt isopaque except at the scanning windows 60, thereim'see Fig. 5, whichwindows are preferably, although not necessarily, square and are ofsmall area and are spacedlengthwise along the belt and also are spacedin a progressive manner transversely of the belt. The number of scanningwindows and their spacing lengthwise of the belt is dependent upon theparticular system on which any particular television signal is broadcastand belts having different numbers of scanning windows, which may bedifierently spaced along the length of the belt, are adapted to beinterchangeably supported on the drum to condition the apparatustoreceive television signals broadcast under different systems. Asspecifically described in'my above referred to application, thescanningbelt herein shown consists of a section ofphotographic and particularlymoving picture film wherein the windows are photographically developed.I

- The driving mechanism for'the' disc includes a synchronous motor 62,the shaft 64 of the rotatable armature of which'is vertically disposedand is rotatable in bearings 66 of the upper and intermediate plates 28and "26, respectively. The motor is secured to a supporting plate 68whichhas upstanding arms 70 between which the lower portion of the'fieldframe of the motor is located and to which arms it is'secur'ed. Saidplate is rotatably supported upon the upper face of an upstandingperipheral flange 72 carried 'by the base plate 20 and has a stud shaft74 which is rotatable in a bearing 76 of said base plate. Said plate 68is pr'ovided with gear teeth 78 on its lower face which mesh with apinion gear 80 fixed to a shaft 582 which is journalled in the baseplate2O and extends through the front wall 12' of the cabinet'andterminates thereat in a knob 84. When the received pictures are out offrame they can be brought into frame by rotating.

theshaft 82 and consequently the field frame of the'motor 62 a suitableamount. This changes'the phase relation of the-received, picture withrespect to the transmitting pic- 86 and a large gear 88 are fixed insuperposed relation on the drum shaft between the intermediate and upperplates 26 and 28. The motor shaft 64 is provided with a driving gear 90having a driving face the width of which is equal to the combined widthof the driving faces of the two gears 86 and 88. A speed-changing frame92 is pivotally supported on a shaft 96 carried by the intermediate andupper frames and has two arms 94 and 95, see especially Fig. 4, whichare located on opposite sides of the driving gear. Idler gears 98 and100, which preferably are identical, are pivoted to the ends of saidarms. When the frame 92 is moved in a counterclockwise direction, Fig.4, the gear 100 is thereby disposed in mesh with the driving gear 90 andthe small gear 86 ofthe drum shaft whereby to establish a high speeddriving connection between the motor and drum. \Vhen the gear frame isswung in a clockwise direction, the gear 100is adapted to be moved outof mesh with itscooperatgears and the gear 98 isadapted to ';be movedinto mesh with the driving gear 90, and the large gear 88 on the drumshaft. A low speed driving connection is thus established between themotor and drum.

The gear frame 92 isprovided with an arm 102 which is loosely extendedthrougha horizontally elongated slot in a plate 104 carried by theintermediate plate 26. -A knob 106, the outer portion of which isinfront of the front wall 12 of the cabinet, is horizontally movable in aslot 108 therein and is siidable on said arm 102 under urge of a spring107 thereon and has a reduced end 110 which can enter a series ofapertures 112 in said plate 104 to lock the gear frame 92 with eitherone of its idler gears in'mesh with the driving and driven gear. It canalso lock said frame in an intermediate position wherein the drumandmotor are. free from a driving connection therebetween.

The front wall 12 of the cabinet is provided with viewing frame or tube114 the inner end of which has a preferably square opening whichconfronts the belt on the drum and in the outer end of wh ch is anenlarging lens 116 located whereby an enlarged image of the receivedpicture can be viewed. A variable source of illumination 118', as agaseous conductor, or neon lamp, is located within the drum in radialline with the scanning belt and lens 116 and has a pair of electrodes120 and 122 of which the electrode120 confronts the belt and lens andconstitutes the variable source of illumination. Thelamp is carried by abracket 124 which issl-idable on a pair ofspaced rods 126- that overliethe top ofthe drum and are secured in'brackets 128 carried bythe-cover14 of the cabinet. A condensing 16118111111, 130 is also slidablycarried bysaid rods and is interposed between windows of thescanningbelt and serves-to concentrate the light of the lamp on the windows. Asthus arranged,'when the cover 14 is raised thelamp and lens areautomatically removed from operative position within the scanning drumso that the drum can be removed for the purpose of applying differentscanningbelts thereon.

The mechanism here shown is simple, ef fective and reliable. It isfreefrom electrical disturbances which would effect the radio receivingand amplifying apparatus associated with the neon lamp and consequentlysaid apparatus can be located in the cabinet herein shown inclose'proximity to the mo.- tor and its associated apparatus and tunedto any desired incoming signal by the tuning device 132. Since thereceiving and amplifying .apparatusforms no part of the presentinvention, it is omitted from the present illustrations.

Iclaim: 1

1. A scanning device for televisionincluding an annular rotatable memberhaving peripherally located alternate supporting surfaces and openingstherein and a-scanning member separate from and supported and carriedbysaid rotatable member upon said surfaces and extended over saidopenings and having scanning windows which are located in register withsaid openings.

2. A scanning device for television includinga rotatable drum having acylindrical periphery provided with openings therein, and an endlessscanning band carried removably by and disposed against said cylindricalperiphery and overlying said openings and havingv scanning windows whichare located at said openings. I

3. A scanning device for television including a rotatable drum having acylindrical'periphery provided with openings therein and a peripheralflange that outstands beyond said periphery and is located belowsaidopenings, and an endless fiexiblescanning belt carried removably by anddisposed against said cylindrical periphery over said openings havingone edge thereof seated upon said flange and having scanning windowstherein which are located at said openings.

4. A scanning device for television including a rotatable drum having adriving hub provided with outstanding driving connected with andupstands above said 7 against deformation by said cylindrlcal pecziposed windows therein.

riphery.

5. A scanning device for television including a rotatable drum having adriving hub provided with outstanding driving arms, and a cylindricalperiphery which is connected with and upstands above said arms and hubsand has openings therein, and an endless flexible scanning beltsupported against'flexing by and seated upon said cy- 'lindricalperiphery over said openings and having windows which are located atsaid openings. 6. Ascanning device for television including a rotatabledrum having lightvpassages and an endless flexible scanning beltcarrieclremova'bly by said druinand'havingex- 7. Scanning apparatusfortelevision including a horizontally rotatable scanning device havinga hub, a vertical drivingshaft for said device loosely located in saidhub andhaving an outstanding flange on which said hub is frictionallyseated, and a lostmotion positive driving connection between said shaftand scanning device including a pin carried by said flange and locatedin an arcuate slot in said hub. 8. Scanning apparatus for televisionincluding a horizontal rotatable scanning device, and means to adaptsaid scanning device to receive'signals transmitted under dif- :ferentsystems including afdrive shaft for said device, a plurality of gears of,diflerent' diameters fixed thereon under said scanning dru1n,'avertical motor-located beneath said scanning device/having an upstandingshaft provided with a driving gear,'speed-changing mechanism locatedbetween and connecting 'said motor and scanning device including amovable frame having arms which are disposed on opposite sides of saidaforesaid gears and have idler gears thereon, and means to move saidframe in opposite directions to bring both idler gears separately intomesh with said driving gear and a sep-- arate one of said other gears.

9.Scanning apparatus for television including a rotatable scanningdevice, and means to adapt said scanning device to receive signalstransmitted under different systems including a drive shaft for saiddevice, a plurality of gears of diflerent diameters fixed thereon, asupporting frame under said scanning device in which said shaft is journaled, a motor under said frame having a vertical shaft provided witha driving gearfarranged in horizontal line with the aforesaidgears,speed-changing mechanism connecting said motor and scanning deviceincluding-a movable frame pivoted on said supportedframe and having armswhich are positions, and also in an intermediate position wherein all ofits idler gears are free from driving connection with the aforesaidgears.

10.Scanning apparatus for television including a vertical driving motorhaving a rotatable armature and a stationary field frame, a scanningdevice havinga support on which it is rotatable, means providing aspeed-reducing 7 driving connection between said armature and scanningdevice, and means to vary the framing of the received picture includingmeans to angularly shift the position of said field frame, thespeedreducing' driving connection providing a small angular displacementof said scanning device for a large angular displacement of said fieldframe, said last mentioned means comprising an annular gear attached tothe 'end of said field frame.

11. Scanning apparatus for television in cluding a supporting base, ahorizontal plate rotatable on said base, a vertical motor having arotary armature and a stationary field frame which latter is supportedby and is fixed to said rotary plate, a scanning device having arotatable support on said base above said motor, means providing adriving connection between said scanning device and motor, and means tovary'the framing of the received picture including means to rotate saidmotor supportingplate on said base, said plate and said base havingfrictionally engaging surfaces which hold said plate and motor fieldframe against any rotary movement caused by the driving reaction betweensaid field frame and motor armature.

12. Scanning apparatus for television including a base, standards risingthereabove, vertically spaced intermediate and upper plates carried bysaid standards, a vertical shaft journalled in said plates, ahorizontally rotatable scanning drum carried by said shaft above saidupper plate and having a removable driving connection therewith, avertical motor located between said standards and mainly below saidintermediate plate having a driving shaft extended into the spacebetween said plates, a gear fixed to said shaft, a second gear fixed tosaid shaft of said scanning drum, means establishing a drivingconnection between said aforesaid gears, a plate rotatable on said baseproviding a support for the field frame of said motor,'and means to varythe framing of the received picture including means to rotate said plateand consequently said motor frame.

13. Scanning apparatus for television ineluding a base, standards risingthereabove, vertically spaced intermediate and upper plates carried bysaid standards, a vertical shaft journalled in said plates, ahorizontally rotatable scanning drum carried by said shaft above saidupper plate and having a removable driving connection therewith, avertical motor located between said standards and mainly below saidintermediate plate having a driving shaft extended into the spacebetween said plates, a gear fixed to said shaft, a second gear fixedtosaid shaft of said scanning drum, means establishing a drivingconnection between said aforesaid gears including a gear frame pivotallylocated between said intermediate and upper plates and pivotallysupported by at least one of said plates having a gear which is movableby movements of said frame into mesh with both aforesaid gears, a platerotatable on said base providing a support for the field frame of saidmotor, and means to vary the framing of the received picture includingmeans to rotate said plate and consequently said motor frame.

14. Television apparatus including a rotatable scanning drum having acylindrical periphery provided with scanning windows, a viewing framelocated exteriorly of said cylindrical periphery, a variable lightsource located within said cylindrical periphery andstationarily-supported means constituting a track which is perpendicularto said cylindrical periphery and to said viewing frame and on whichsaid variable light source is guided for movements toward and away fromsaid viewing frame.

15. Television apparatus including a rotatable scanning drum having acylindrical periphery provided with scanning windows, a viewing framelocated exteriorly of said cylindrical periphery, a variable lightsource located within said cylindrical periphery, a condensing lenslocated between said periphery and variable light source, and supportingmeans for said lens and variable light source constituting a track whichis perpendicular to said cylindrical periphery and to said viewing frameon which both are independently movable in the same line toward and awayfrom said viewing frame.

16. Television apparatus including an enclosing cabinet having a fixedviewing frame and a removable cover, scanning mechanism includingarotatable scanning device which is located under said cover and has aremovable windowed scanning member, and a variable light source carriedby said cover on the side of said scanning device opposite said viewingframe, said variable light source be ing automatically removable fromits aforesaid position when said cover is removed from closing relationwith the cabinet so that said removable scanning member is accessiblefor instant removal.

17 Television apparatus including an enclosing casing having an open topand a cover removably closing said top, a viewing frame located in aside wall of said cabinet beneath said top, scanning apparatus locatedwithin said cabinet including a horizontally disposed rotatable scanningdrum having on and removably connected with its periphery a scanningband provided with scanning windows and located immediately under saidcover in

